Ediacara fossils often exhibit enigmatic taphonomy that complicates morphological characterization and ecological and phylogenetic interpretation; such is the case with Pteridinium simplex from the late Ediacaran Kliphoek Member in southern Namibia. Pteridinium simplex is often preserved as three-dimensional (3D) casts and molds in coarse-grained quartzites, making detailed morphological characterization difficult. In addition, P. simplex is often transported, distorted, and embedded in gutter fills or channel deposits, further obscuring its morphologies. By utilizing microfocus X-ray computed tomography (microCT) techniques, we are able to trace individual specimens and their vanes in order to digitally restore the 3D morphology of this enigmatic fossil. Our analysis shows that P. simplex has a very flexible integument that can be bent, folded, twisted, stretched, and torn, indicating a certain degree of elasticity. We find no evidence for vane identity change or penetrative growth that were previously used as evidence to support a fully endobenthic lifestyle of P. simplex; instead, the traditional interpretation of a semi-endobenthic or epibenthic lifestyle is favored. The elastic integument of P. simplex is inconsistent with a phylogenetic affinity with xenophyophore protists; instead, its physical property is consistent with the presence of collagen and cellulose, an inference that would provide constraints on the phylogenetic affinity of P. simplex.

Click here to download the original scan data for slab 2 (1.8 Gb) and here to download the original scan data for slab 3 (1.5 Gb).

About the Species

This specimen was collected from the upper Kliphoek Member of the Dabis Formation, Kuibis Subgroup, located at Aar Farm in the Aus region of southern Namibia. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Michael Meyer of Western Carolina University and Dr. Shuhai Xiao of Virginia Tech. Funding for scanning was provided by Dr. Xiao (NSF grant EAR-0844235).

About this Specimen

This specimen was scanned by Matthew Colbert as two separate slabs. Slab 2 (smaller piece) was scanned on 12 June 2012 horizontally for a total of 1312 slices. Each 1024 x 1024 pixel slice is 0.096 mm thick, with an interslice spacing of 0.096 mm and a field of reconstruction of 91 mm. Slab 3 (larger piece) was scanned on 19 September 2012 horizontally for a total of 1083 slices. Each 1024 x 1024 pixel slice is 0.115 mm thick, with an interslice spacing of 0.115 mm and a field of reconstruction of 107 mm.